including pesticides, are capable of inducing oxidative stress in fish (Sayeed et al., 2003 and Monteiro et al., 2006). This event results in the formation of highly reactive compounds such as free radicals or oxy-radicals that frequently react with cellular macromolecules, leading potentially to enzyme inactivation, lipid peroxidation, DNA damage and even cell death (Van der Oost et al., 2003). Impairment in anti-oxidative enzymes will produce an imbalance between pro- and antioxidant system causing the formation of toxic hydroxyl radicals with direct consequences on cell integrity and cell function itself (Winston and DiGiulio, 1991).